mybatis常用分页插件，快速分页处理

在未分享整个查询分页的执行代码之前，先了解一下执行流程。

1.总体上是利用mybatis的插件拦截器，在sql执行之前拦截，为查询语句加上limit X X

2.用一个Page对象，贯穿整个执行流程，这个Page对象需要用java编写前端分页组件

3.用一套比较完整的三层entity，dao，service支持这个分页架构

4.这个分页用到的一些辅助类

注：分享的内容较多，这边的话我就不把需要的jar一一列举，大家使用这个分页功能的时候缺少什么就去晚上找什么jar包即可，尽可能用maven包导入因为maven能减少版本冲突等比较好的优势。我只能说尽可能让大家快速使用这个比较好用的分页功能，如果讲得不明白，欢迎加我QQ一起探讨1063150576,。莫喷哈！还有就是文章篇幅可能会比较大，不过花点时间，把它看完并实践一下一定会收获良多。

第一步：既然主题是围绕怎么进行分页的，我们就从mybatis入手，首先，我们把mybatis相关的两个比较重要的配置文件拿出来做简要的理解，一个是mybatis-config.xml，另外一个是实体所对应的mapper配置文件，我会在配置文件上写好注释，大家一看就会明白。

mybatis-config.xml

<!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration><!-- 全局参数 --><settings><!-- 使全局的映射器启用或禁用缓存。 --><setting name="cacheEnabled" value="false"/><!-- 全局启用或禁用延迟加载。当禁用时，所有关联对象都会即时加载。 --><setting name="lazyLoadingEnabled" value="true"/><!-- 当启用时，有延迟加载属性的对象在被调用时将会完全加载任意属性。否则，每种属性将会按需要加载。 --><setting name="aggressiveLazyLoading" value="true"/><!-- 是否允许单条sql 返回多个数据集  (取决于驱动的兼容性) default:true --><setting name="multipleResultSetsEnabled" value="true"/><!-- 是否可以使用列的别名 (取决于驱动的兼容性) default:true --><setting name="useColumnLabel" value="true"/><!-- 允许JDBC 生成主键。需要驱动器支持。如果设为了true，这个设置将强制使用被生成的主键，有一些驱动器不兼容不过仍然可以执行。  default:false  --><setting name="useGeneratedKeys" value="false"/><!-- 指定 MyBatis 如何自动映射 数据基表的列 NONE：不隐射　PARTIAL:部分  FULL:全部  -->  <setting name="autoMappingBehavior" value="PARTIAL"/><!-- 这是默认的执行类型  （SIMPLE: 简单； REUSE: 执行器可能重复使用prepared statements语句；BATCH: 执行器可以重复执行语句和批量更新）  --><setting name="defaultExecutorType" value="SIMPLE"/><!-- 使用驼峰命名法转换字段。 --><setting name="mapUnderscoreToCamelCase" value="true"/><!-- 设置本地缓存范围 session:就会有数据的共享  statement:语句范围 (这样就不会有数据的共享 ) defalut:session --><setting name="localCacheScope" value="SESSION"/><!-- 设置但JDBC类型为空时,某些驱动程序 要指定值,default:OTHER，插入空值时不需要指定类型 --><setting name="jdbcTypeForNull" value="NULL"/><setting name="logPrefix" value="dao."/></settings><!--别名是一个较短的Java 类型的名称 --><typeAliases><typeAlias type="com.store.base.model.StoreUser"alias="User"></typeAlias>          <typeAlias type="com.store.base.secondmodel.pratice.model.Product"alias="Product"></typeAlias>            <typeAlias type="com.store.base.secondmodel.base.Page"alias="Page"></typeAlias>           </typeAliases><!-- 插件配置,这边为mybatis配置分页拦截器，这个分页拦截器需要我们自己实现 --><plugins><plugin interceptor="com.store.base.secondmodel.base.pageinterceptor.PaginationInterceptor" /></plugins></configuration>

一个ProductMapper.xml作为测试对象，这个mapper文件就简单配置一个需要用到的查询语句

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.store.base.secondmodel.pratice.dao.ProductDao" ><sql id="baseColumns" >id, product_name as productName, product_no as productNo, price as price</sql><select id="findList" resultType="com.store.base.secondmodel.pratice.model.Product">select <include refid="baseColumns"/> from t_store_product</select></mapper>

第二步：接下去主要针对这个分页拦截器进行深入分析学习，主要有以下几个类和其对应接口

（1）BaseInterceptor 拦截器基础类

（2）PaginationInterceptor 我们要使用的分页插件类，继承上面基础类

（3）SQLHelper 主要是用来提前执行count语句，还有就是获取整个完整的分页语句

（4）Dialect，MysqlDialect,主要用来数据库是否支持limit语句，然后封装完整limit语句

以下是这几个类的分享展示

BaseInterceptor.java

package com.store.base.secondmodel.base.pageinterceptor;import java.io.Serializable;
import java.util.Properties;import org.apache.ibatis.logging.Log;
import org.apache.ibatis.logging.LogFactory;
import org.apache.ibatis.plugin.Interceptor;import com.store.base.secondmodel.base.Global;
import com.store.base.secondmodel.base.Page;
import com.store.base.secondmodel.base.dialect.Dialect;
import com.store.base.secondmodel.base.dialect.MySQLDialect;
import com.store.base.util.Reflections;/*** Mybatis分页拦截器基类* @author **/
public abstract class BaseInterceptor implements Interceptor, Serializable {private static final long serialVersionUID = 1L;protected static final String PAGE = "page";protected static final String DELEGATE = "delegate";protected static final String MAPPED_STATEMENT = "mappedStatement";protected Log log = LogFactory.getLog(this.getClass());protected Dialect DIALECT;/*** 对参数进行转换和检查* @param parameterObject 参数对象* @param page            分页对象* @return 分页对象* @throws NoSuchFieldException 无法找到参数*/@SuppressWarnings("unchecked")protected static Page<Object> convertParameter(Object parameterObject, Page<Object> page) {try{if (parameterObject instanceof Page) {return (Page<Object>) parameterObject;} else {return (Page<Object>)Reflections.getFieldValue(parameterObject, PAGE);}}catch (Exception e) {return null;}}/*** 设置属性，支持自定义方言类和制定数据库的方式* <code>dialectClass</code>,自定义方言类。可以不配置这项* <ode>dbms</ode> 数据库类型，插件支持的数据库* <code>sqlPattern</code> 需要拦截的SQL ID* @param p 属性*/protected void initProperties(Properties p) {Dialect dialect = null;String dbType = Global.getConfig("jdbc.type");if("mysql".equals(dbType)){dialect = new MySQLDialect();}if (dialect == null) {throw new RuntimeException("mybatis dialect error.");}DIALECT = dialect;}
}

PaginationInterceptor.java

package com.store.base.secondmodel.base.pageinterceptor;import java.util.Properties;import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.SqlSource;
import org.apache.ibatis.plugin.Intercepts;
import org.apache.ibatis.plugin.Invocation;
import org.apache.ibatis.plugin.Plugin;
import org.apache.ibatis.plugin.Signature;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;import com.store.base.secondmodel.base.Page;
import com.store.base.secondmodel.base.util.StringUtils;
import com.store.base.util.Reflections;/*** 数据库分页插件，只拦截查询语句.* @author * */
@Intercepts({ @Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class,ResultHandler.class }) })
public class PaginationInterceptor extends BaseInterceptor {private static final long serialVersionUID = 1L;@Overridepublic Object intercept(Invocation invocation) throws Throwable {final MappedStatement mappedStatement = (MappedStatement) invocation.getArgs()[0];Object parameter = invocation.getArgs()[1];BoundSql boundSql = mappedStatement.getBoundSql(parameter);Object parameterObject = boundSql.getParameterObject();// 获取分页参数对象Page<Object> page = null;if (parameterObject != null) {page = convertParameter(parameterObject, page);}// 如果设置了分页对象，则进行分页if (page != null && page.getPageSize() != -1) {if (StringUtils.isBlank(boundSql.getSql())) {return null;}String originalSql = boundSql.getSql().trim();// 得到总记录数page.setCount(SQLHelper.getCount(originalSql, null,mappedStatement, parameterObject, boundSql, log));// 分页查询 本地化对象 修改数据库注意修改实现String pageSql = SQLHelper.generatePageSql(originalSql, page,DIALECT);invocation.getArgs()[2] = new RowBounds(RowBounds.NO_ROW_OFFSET,RowBounds.NO_ROW_LIMIT);BoundSql newBoundSql = new BoundSql(mappedStatement.getConfiguration(), pageSql,boundSql.getParameterMappings(),boundSql.getParameterObject());// 解决MyBatis 分页foreach 参数失效 startif (Reflections.getFieldValue(boundSql, "metaParameters") != null) {MetaObject mo = (MetaObject) Reflections.getFieldValue(boundSql, "metaParameters");Reflections.setFieldValue(newBoundSql, "metaParameters", mo);}// 解决MyBatis 分页foreach 参数失效 endMappedStatement newMs = copyFromMappedStatement(mappedStatement,new BoundSqlSqlSource(newBoundSql));invocation.getArgs()[0] = newMs;}return invocation.proceed();}@Overridepublic Object plugin(Object target) {return Plugin.wrap(target, this);}@Overridepublic void setProperties(Properties properties) {super.initProperties(properties);}private MappedStatement copyFromMappedStatement(MappedStatement ms,SqlSource newSqlSource) {MappedStatement.Builder builder = new MappedStatement.Builder(ms.getConfiguration(), ms.getId(), newSqlSource,ms.getSqlCommandType());builder.resource(ms.getResource());builder.fetchSize(ms.getFetchSize());builder.statementType(ms.getStatementType());builder.keyGenerator(ms.getKeyGenerator());if (ms.getKeyProperties() != null) {for (String keyProperty : ms.getKeyProperties()) {builder.keyProperty(keyProperty);}}builder.timeout(ms.getTimeout());builder.parameterMap(ms.getParameterMap());builder.resultMaps(ms.getResultMaps());builder.cache(ms.getCache());return builder.build();}public static class BoundSqlSqlSource implements SqlSource {BoundSql boundSql;public BoundSqlSqlSource(BoundSql boundSql) {this.boundSql = boundSql;}@Overridepublic BoundSql getBoundSql(Object parameterObject) {return boundSql;}}}

SQLHelper.java

package com.store.base.secondmodel.base.pageinterceptor;import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.executor.ExecutorException;
import org.apache.ibatis.logging.Log;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.ParameterMapping;
import org.apache.ibatis.mapping.ParameterMode;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.reflection.property.PropertyTokenizer;
import org.apache.ibatis.scripting.xmltags.ForEachSqlNode;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.type.TypeHandler;
import org.apache.ibatis.type.TypeHandlerRegistry;import com.store.base.secondmodel.base.Global;
import com.store.base.secondmodel.base.Page;
import com.store.base.secondmodel.base.dialect.Dialect;
import com.store.base.secondmodel.base.util.StringUtils;
import com.store.base.util.Reflections;/*** SQL工具类* @author **/
public class SQLHelper {/*** 默认私有构造函数*/private SQLHelper() {}/*** 对SQL参数(?)设值,参考org.apache.ibatis.executor.parameter.DefaultParameterHandler** @param ps              表示预编译的 SQL 语句的对象。* @param mappedStatement MappedStatement* @param boundSql        SQL* @param parameterObject 参数对象* @throws java.sql.SQLException 数据库异常*/@SuppressWarnings("unchecked")public static void setParameters(PreparedStatement ps, MappedStatement mappedStatement, BoundSql boundSql, Object parameterObject) throws SQLException {ErrorContext.instance().activity("setting parameters").object(mappedStatement.getParameterMap().getId());List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();if (parameterMappings != null) {Configuration configuration = mappedStatement.getConfiguration();TypeHandlerRegistry typeHandlerRegistry = configuration.getTypeHandlerRegistry();MetaObject metaObject = parameterObject == null ? null :configuration.newMetaObject(parameterObject);for (int i = 0; i < parameterMappings.size(); i++) {ParameterMapping parameterMapping = parameterMappings.get(i);if (parameterMapping.getMode() != ParameterMode.OUT) {Object value;String propertyName = parameterMapping.getProperty();PropertyTokenizer prop = new PropertyTokenizer(propertyName);if (parameterObject == null) {value = null;} else if (typeHandlerRegistry.hasTypeHandler(parameterObject.getClass())) {value = parameterObject;} else if (boundSql.hasAdditionalParameter(propertyName)) {value = boundSql.getAdditionalParameter(propertyName);} else if (propertyName.startsWith(ForEachSqlNode.ITEM_PREFIX) && boundSql.hasAdditionalParameter(prop.getName())) {value = boundSql.getAdditionalParameter(prop.getName());if (value != null) {value = configuration.newMetaObject(value).getValue(propertyName.substring(prop.getName().length()));}} else {value = metaObject == null ? null : metaObject.getValue(propertyName);}@SuppressWarnings("rawtypes")TypeHandler typeHandler = parameterMapping.getTypeHandler();if (typeHandler == null) {throw new ExecutorException("There was no TypeHandler found for parameter " + propertyName + " of statement " + mappedStatement.getId());}typeHandler.setParameter(ps, i + 1, value, parameterMapping.getJdbcType());}}}}/*** 查询总纪录数* @param sql             SQL语句* @param connection      数据库连接* @param mappedStatement mapped* @param parameterObject 参数* @param boundSql        boundSql* @return 总记录数* @throws SQLException sql查询错误*/public static int getCount(final String sql, final Connection connection,final MappedStatement mappedStatement, final Object parameterObject,final BoundSql boundSql, Log log) throws SQLException {String dbName = Global.getConfig("jdbc.type");final String countSql;if("oracle".equals(dbName)){countSql = "select count(1) from (" + sql + ") tmp_count";}else{countSql = "select count(1) from (" + removeOrders(sql) + ") tmp_count";}Connection conn = connection;PreparedStatement ps = null;ResultSet rs = null;try {if (log.isDebugEnabled()) {log.debug("COUNT SQL: " + StringUtils.replaceEach(countSql, new String[]{"\n","\t"}, new String[]{" "," "}));}if (conn == null){conn = mappedStatement.getConfiguration().getEnvironment().getDataSource().getConnection();}ps = conn.prepareStatement(countSql);BoundSql countBS = new BoundSql(mappedStatement.getConfiguration(), countSql,boundSql.getParameterMappings(), parameterObject);//解决MyBatis 分页foreach 参数失效 startif (Reflections.getFieldValue(boundSql, "metaParameters") != null) {MetaObject mo = (MetaObject) Reflections.getFieldValue(boundSql, "metaParameters");Reflections.setFieldValue(countBS, "metaParameters", mo);}//解决MyBatis 分页foreach 参数失效 end SQLHelper.setParameters(ps, mappedStatement, countBS, parameterObject);rs = ps.executeQuery();int count = 0;if (rs.next()) {count = rs.getInt(1);}return count;} finally {if (rs != null) {rs.close();}if (ps != null) {ps.close();}if (conn != null) {conn.close();}}}/*** 根据数据库方言，生成特定的分页sql* @param sql     Mapper中的Sql语句* @param page    分页对象* @param dialect 方言类型* @return 分页SQL*/public static String generatePageSql(String sql, Page<Object> page, Dialect dialect) {if (dialect.supportsLimit()) {return dialect.getLimitString(sql, page.getFirstResult(), page.getMaxResults());} else {return sql;}}/** * 去除qlString的select子句。 * @param hql * @return */  @SuppressWarnings("unused")private static String removeSelect(String qlString){  int beginPos = qlString.toLowerCase().indexOf("from");  return qlString.substring(beginPos);  }  /** * 去除hql的orderBy子句。 * @param hql * @return */  private static String removeOrders(String qlString) {  Pattern p = Pattern.compile("order\\s*by[\\w|\\W|\\s|\\S]*", Pattern.CASE_INSENSITIVE);  Matcher m = p.matcher(qlString);  StringBuffer sb = new StringBuffer();  while (m.find()) {  m.appendReplacement(sb, "");  }m.appendTail(sb);return sb.toString();  }
}

Dialect.java 接口

package com.store.base.secondmodel.base.dialect;/*** 类似hibernate的Dialect,但只精简出分页部分* @author **/
public interface Dialect {/*** 数据库本身是否支持分页当前的分页查询方式* 如果数据库不支持的话，则不进行数据库分页** @return true：支持当前的分页查询方式*/public boolean supportsLimit();/*** 将sql转换为分页SQL，分别调用分页sql** @param sql    SQL语句* @param offset 开始条数* @param limit  每页显示多少纪录条数* @return 分页查询的sql*/public String getLimitString(String sql, int offset, int limit);}

MySQLDialect.java

package com.store.base.secondmodel.base.dialect;/*** Mysql方言的实现* @author **/
public class MySQLDialect implements Dialect {@Overridepublic boolean supportsLimit() {return true;}@Overridepublic String getLimitString(String sql, int offset, int limit) {return getLimitString(sql, offset, Integer.toString(offset),Integer.toString(limit));}/*** 将sql变成分页sql语句,提供将offset及limit使用占位符号(placeholder)替换.* <pre>* 如mysql* dialect.getLimitString("select * from user", 12, ":offset",0,":limit") 将返回* select * from user limit :offset,:limit* </pre>** @param sql               实际SQL语句* @param offset            分页开始纪录条数* @param offsetPlaceholder 分页开始纪录条数－占位符号* @param limitPlaceholder  分页纪录条数占位符号* @return 包含占位符的分页sql*/public String getLimitString(String sql, int offset, String offsetPlaceholder, String limitPlaceholder) {StringBuilder stringBuilder = new StringBuilder(sql);stringBuilder.append(" limit ");if (offset > 0) {stringBuilder.append(offsetPlaceholder).append(",").append(limitPlaceholder);} else {stringBuilder.append(limitPlaceholder);}return stringBuilder.toString();}
}

差不多到这边已经把整块分页怎么实现的给分享完了，但是我们还有更重要的任务，想要整个东西跑起来，肯定还要有基础工作要做，接下去我们分析整套Page对象以及它所依据的三层架构，还是用product作为实体进行分析。一整套三层架构讲下来，收获肯定又满满的。我们依次从entity->dao->service的顺序讲下来。

首先，针对我们的实体得继承两个抽象实体类BaseEntity 与 DataEntity

BaseEntity.java 主要放置Page成员变量，继承它后就可以每个实体都拥有这个成员变量

package com.store.base.secondmodel.base;import java.io.Serializable;
import java.util.Map;import javax.xml.bind.annotation.XmlTransient;import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.builder.ReflectionToStringBuilder;import com.fasterxml.jackson.annotation.JsonIgnore;
import com.google.common.collect.Maps;
import com.store.base.model.StoreUser;/*** 最顶层的Entity* @author ** @param <T>*/
public abstract class BaseEntity<T> implements Serializable {private static final long serialVersionUID = 1L;/*** 删除标记（0：正常；1：删除；2：审核；）*/public static final String DEL_FLAG_NORMAL = "0";public static final String DEL_FLAG_DELETE = "1";public static final String DEL_FLAG_AUDIT = "2";/*** 实体编号（唯一标识）*/protected String id;/*** 当前用户*/protected StoreUser currentUser;/*** 当前实体分页对象*/protected Page<T> page;/*** 自定义SQL（SQL标识，SQL内容）*/private Map<String, String> sqlMap;public BaseEntity() {}public BaseEntity(String id) {this();this.id = id;}public String getId() {return id;}public void setId(String id) {this.id = id;}/*** 这个主要针对shiro执行插入更新的时候会调用，获取当前的用户* @return*/@JsonIgnore@XmlTransientpublic StoreUser getCurrentUser() {if(currentUser == null){
//          currentUser = UserUtils.getUser();}return currentUser;}public void setCurrentUser(StoreUser currentUser) {this.currentUser = currentUser;}@JsonIgnore@XmlTransientpublic Page<T> getPage() {if (page == null){page = new Page<>();}return page;}public Page<T> setPage(Page<T> page) {this.page = page;return page;}@JsonIgnore@XmlTransientpublic Map<String, String> getSqlMap() {if (sqlMap == null){sqlMap = Maps.newHashMap();}return sqlMap;}public void setSqlMap(Map<String, String> sqlMap) {this.sqlMap = sqlMap;}/*** 插入之前执行方法，子类实现*/public abstract void preInsert();/*** 更新之前执行方法，子类实现*/public abstract void preUpdate();/*** 是否是新记录（默认：false），调用setIsNewRecord()设置新记录，使用自定义ID。* 设置为true后强制执行插入语句，ID不会自动生成，需从手动传入。* @return*/public boolean getIsNewRecord() {return StringUtils.isBlank(getId());}/*** 全局变量对象*/@JsonIgnorepublic Global getGlobal() {return Global.getInstance();}/*** 获取数据库名称*/@JsonIgnorepublic String getDbName(){return Global.getConfig("jdbc.type");}@Overridepublic String toString() {return ReflectionToStringBuilder.toString(this);}}

DataEntity.java,主要存储更新删除时间，创建用户，更新用户，逻辑删除标志等

package com.store.base.secondmodel.base;import java.util.Date;import org.hibernate.validator.constraints.Length;import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.store.base.model.StoreUser;/*** 数据Entity* @author ** @param <T>*/
public abstract class DataEntity<T> extends BaseEntity<T> {private static final long serialVersionUID = 1L;protected StoreUser createBy; // 创建者protected Date createDate; // 创建日期protected StoreUser updateBy; // 更新者protected Date updateDate; // 更新日期protected String delFlag; // 删除标记（0：正常；1：删除；2：审核）public DataEntity() {super();this.delFlag = DEL_FLAG_NORMAL;}public DataEntity(String id) {super(id);}/*** 插入之前执行方法，需要手动调用*/@Overridepublic void preInsert() {// 不限制ID为UUID，调用setIsNewRecord()使用自定义ID
//      User user = UserUtils.getUser();
//      if (StringUtils.isNotBlank(user.getId())) {
//          this.updateBy = user;
//          this.createBy = user;
//      }this.updateDate = new Date();this.createDate = this.updateDate;}/*** 更新之前执行方法，需要手动调用*/@Overridepublic void preUpdate() {
//      User user = UserUtils.getUser();
//      if (StringUtils.isNotBlank(user.getId())) {
//          this.updateBy = user;
//      }this.updateDate = new Date();}//  @JsonIgnorepublic StoreUser getCreateBy() {return createBy;}public void setCreateBy(StoreUser createBy) {this.createBy = createBy;}@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")public Date getCreateDate() {return createDate;}public void setCreateDate(Date createDate) {this.createDate = createDate;}//  @JsonIgnorepublic StoreUser getUpdateBy() {return updateBy;}public void setUpdateBy(StoreUser updateBy) {this.updateBy = updateBy;}@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")public Date getUpdateDate() {return updateDate;}public void setUpdateDate(Date updateDate) {this.updateDate = updateDate;}@JsonIgnore@Length(min = 1, max = 1)public String getDelFlag() {return delFlag;}public void setDelFlag(String delFlag) {this.delFlag = delFlag;}}

Product.java 产品类

package com.store.base.secondmodel.pratice.model;import com.store.base.secondmodel.base.DataEntity;/***产品基础类*2016年10月11日**/
public class Product extends DataEntity<Product>{private static final long serialVersionUID = 1L;private String productName;private float price;private String productNo;public String getProductName() {return productName;}public void setProductName(String productName) {this.productName = productName;}public float getPrice() {return price;}public void setPrice(float price) {this.price = price;}public String getProductNo() {return productNo;}public void setProductNo(String productNo) {this.productNo = productNo;}}

怎么样，是不是看到很复杂的一个实体继承连关系，不过这有什么，越复杂就会越完整。接下来我就看看dao层，同样是三层，准备好接受洗礼吧

BaseDao.java 预留接口

package com.store.base.secondmodel.base;/*** 最顶层的DAO接口* @author **/
public interface BaseDao {}

CrudDao.java 针对增删改查的一个dao接口层

package com.store.base.secondmodel.base;import java.util.List;/*** 定义增删改查的DAO接口* @author ** @param <T>*/
public interface CrudDao<T> extends BaseDao {/*** 获取单条数据* @param id* @return*/public T get(String id);/*** 获取单条数据* @param entity* @return*/public T get(T entity);/*** 查询数据列表，如果需要分页，请设置分页对象，如：entity.setPage(new Page<T>());* @param entity* @return*/public List<T> findList(T entity);/*** 查询所有数据列表* @param entity* @return*/public List<T> findAllList(T entity);/*** 查询所有数据列表* @see public List<T> findAllList(T entity)* @returnpublic List<T> findAllList();*//*** 插入数据* @param entity* @return*/public int insert(T entity);/*** 更新数据* @param entity* @return*/public int update(T entity);/*** 删除数据（一般为逻辑删除，更新del_flag字段为1）* @param id* @see public int delete(T entity)* @return*/public int delete(String id);/*** 删除数据（一般为逻辑删除，更新del_flag字段为1）* @param entity* @return*/public int delete(T entity);
}

ProductDao.java mybatis对应的接口mapper，同时也是dao实现，这边需要自定一个注解@MyBatisRepository

package com.store.base.secondmodel.pratice.dao;import com.store.base.secondmodel.base.CrudDao;
import com.store.base.secondmodel.base.MyBatisRepository;
import com.store.base.secondmodel.pratice.model.Product;/***TODO*2016年10月11日**/
@MyBatisRepository
public interface ProductDao extends CrudDao<Product>{}

自定义注解MyBatisRepository.java，跟自定义注解相关，这里就不做过多的解读，网上资料一堆

package com.store.base.secondmodel.base;import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.ElementType;import org.springframework.stereotype.Component;/*** 标识MyBatis的DAO,方便{@link org.mybatis.spring.mapper.MapperScannerConfigurer}的扫描。* * 请注意要在spring的配置文件中配置扫描该注解类的配置*    *<bean id="mapperScannerConfigurer" class="org.mybatis.spring.mapper.MapperScannerConfigurer">*<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />*<property name="basePackage" value="com.store.base.secondmodel" />*<property name="annotationClass" value="com.store.base.secondmodel.base.MyBatisRepository" />*</bean>* @author * */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Component
public @interface MyBatisRepository {String value() default "";
}

注意：跟ProductDao.java联系比较大的是ProductMapper.xml文件，大家可以看到上面那个配置文件的namespace是指向这个dao的路径的。

接下来我们就进入最后的service分析了，一样还是三层继承

BaseService.java

package com.store.base.secondmodel.base;import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.transaction.annotation.Transactional;/*** Service的最顶层父类* @author **/
@Transactional(readOnly = true)
public abstract class BaseService {//日志记录用的protected Logger logger = LoggerFactory.getLogger(getClass());
}

CrudService.java 增删改查相关的业务接口实现

package com.store.base.secondmodel.base;import java.util.List;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.transaction.annotation.Transactional;/*** 增删改查Service基类* @author ** @param <D>* @param <T>*/
public abstract class CrudService<D extends CrudDao<T>, T extends DataEntity<T>>extends BaseService {/*** 持久层对象*/@Autowiredprotected D dao;/*** 获取单条数据* @param id* @return*/public T get(String id) {return dao.get(id);}/*** 获取单条数据* @param entity* @return*/public T get(T entity) {return dao.get(entity);}/*** 查询列表数据* @param entity* @return*/public List<T> findList(T entity) {return dao.findList(entity);}/*** 查询分页数据* @param page 分页对象* @param entity* @return*/public Page<T> findPage(Page<T> page, T entity) {entity.setPage(page);page.setList(dao.findList(entity));return page;}/*** 保存数据（插入或更新）* @param entity*/@Transactional(readOnly = false)public void save(T entity) {if (entity.getIsNewRecord()){entity.preInsert();dao.insert(entity);}else{entity.preUpdate();dao.update(entity);}}/*** 删除数据* @param entity*/@Transactional(readOnly = false)public void delete(T entity) {dao.delete(entity);}
}

ProductService.java,去继承CrudService接口，注意起注入dao和实体类型的一种模式

package com.store.base.secondmodel.pratice.service;import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;import com.store.base.secondmodel.base.CrudService;
import com.store.base.secondmodel.pratice.dao.ProductDao;
import com.store.base.secondmodel.pratice.model.Product;/***TODO*2016年10月11日*
@Service
@Transactional(readOnly = true)
public class ProductService extends CrudService<ProductDao,Product>{}

我想看到这里的同志已经很不耐烦了。但是如果你错过接下去的一段，基本上刚才看的就快等于白看了，革命的胜利就在后半段，因为整个分页功能围绕的就是一个Page对象，重磅内容终于要出来了，当你把Page对象填充到刚才那个BaseEntity上的时候，你会发现一切就完整起来了，废话不多说，Page对象如下

package com.store.base.secondmodel.base;import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Pattern;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import com.fasterxml.jackson.annotation.JsonIgnore;
import com.store.base.secondmodel.base.util.CookieUtils;
import com.store.base.secondmodel.base.util.StringUtils;/*** 分页类* @author ** @param <T>*/
public class Page<T> implements Serializable{private static final long serialVersionUID = 1L;private int pageNo = 1; // 当前页码private int pageSize = Integer.parseInt(Global.getConfig("page.pageSize")); // 页面大小，设置为“-1”表示不进行分页（分页无效）private long count;// 总记录数，设置为“-1”表示不查询总数private int first;// 首页索引private int last;// 尾页索引private int prev;// 上一页索引private int next;// 下一页索引private boolean firstPage;//是否是第一页private boolean lastPage;//是否是最后一页private int length = 6;// 显示页面长度private int slider = 1;// 前后显示页面长度private List<T> list = new ArrayList<>();private String orderBy = ""; // 标准查询有效， 实例： updatedate desc, name ascprivate String funcName = "page"; // 设置点击页码调用的js函数名称，默认为page，在一页有多个分页对象时使用。private String funcParam = ""; // 函数的附加参数，第三个参数值。private String message = ""; // 设置提示消息，显示在“共n条”之后public Page() {this.pageSize = -1;}/*** 构造方法* @param request 传递 repage 参数，来记住页码* @param response 用于设置 Cookie，记住页码*/public Page(HttpServletRequest request, HttpServletResponse response){this(request, response, -2);}/*** 构造方法* @param request 传递 repage 参数，来记住页码* @param response 用于设置 Cookie，记住页码* @param defaultPageSize 默认分页大小，如果传递 -1 则为不分页，返回所有数据*/public Page(HttpServletRequest request, HttpServletResponse response, int defaultPageSize){// 设置页码参数（传递repage参数，来记住页码）String no = request.getParameter("pageNo");if (StringUtils.isNumeric(no)){CookieUtils.setCookie(response, "pageNo", no);this.setPageNo(Integer.parseInt(no));}else if (request.getParameter("repage")!=null){no = CookieUtils.getCookie(request, "pageNo");if (StringUtils.isNumeric(no)){this.setPageNo(Integer.parseInt(no));}}// 设置页面大小参数（传递repage参数，来记住页码大小）String size = request.getParameter("pageSize");if (StringUtils.isNumeric(size)){CookieUtils.setCookie(response, "pageSize", size);this.setPageSize(Integer.parseInt(size));}else if (request.getParameter("repage")!=null){no = CookieUtils.getCookie(request, "pageSize");if (StringUtils.isNumeric(size)){this.setPageSize(Integer.parseInt(size));}}else if (defaultPageSize != -2){this.pageSize = defaultPageSize;}// 设置排序参数String orderBy = request.getParameter("orderBy");if (StringUtils.isNotBlank(orderBy)){this.setOrderBy(orderBy);}}/*** 构造方法* @param pageNo 当前页码* @param pageSize 分页大小*/public Page(int pageNo, int pageSize) {this(pageNo, pageSize, 0);}/*** 构造方法* @param pageNo 当前页码* @param pageSize 分页大小* @param count 数据条数*/public Page(int pageNo, int pageSize, long count) {this(pageNo, pageSize, count, new ArrayList<T>());}/*** 构造方法* @param pageNo 当前页码* @param pageSize 分页大小* @param count 数据条数* @param list 本页数据对象列表*/public Page(int pageNo, int pageSize, long count, List<T> list) {this.setCount(count);this.setPageNo(pageNo);this.pageSize = pageSize;this.list = list;}/*** 初始化参数*/public void initialize(){//1this.first = 1;this.last = (int)(count / (this.pageSize < 1 ? 20 : this.pageSize) + first - 1);if (this.count % this.pageSize != 0 || this.last == 0) {this.last++;}if (this.last < this.first) {this.last = this.first;}if (this.pageNo <= 1) {this.pageNo = this.first;this.firstPage=true;}if (this.pageNo >= this.last) {this.pageNo = this.last;this.lastPage=true;}if (this.pageNo < this.last - 1) {this.next = this.pageNo + 1;} else {this.next = this.last;}if (this.pageNo > 1) {this.prev = this.pageNo - 1;} else {this.prev = this.first;}//2if (this.pageNo < this.first) {// 如果当前页小于首页this.pageNo = this.first;}if (this.pageNo > this.last) {// 如果当前页大于尾页this.pageNo = this.last;}}/*** 默认输出当前分页标签 * <div class="page">${page}</div>*/@Overridepublic String toString() {StringBuilder sb = new StringBuilder();if (pageNo == first) {// 如果是首页sb.append("<li class=\"disabled\"><a href=\"javascript:\">« 上一页</a></li>\n");} else {sb.append("<li><a href=\"javascript:\" οnclick=\""+funcName+"("+prev+","+pageSize+",'"+funcParam+"');\">« 上一页</a></li>\n");}int begin = pageNo - (length / 2);if (begin < first) {begin = first;}int end = begin + length - 1;if (end >= last) {end = last;begin = end - length + 1;if (begin < first) {begin = first;}}if (begin > first) {int i = 0;for (i = first; i < first + slider && i < begin; i++) {sb.append("<li><a href=\"javascript:\" οnclick=\""+funcName+"("+i+","+pageSize+",'"+funcParam+"');\">"+ (i + 1 - first) + "</a></li>\n");}if (i < begin) {sb.append("<li class=\"disabled\"><a href=\"javascript:\">...</a></li>\n");}}for (int i = begin; i <= end; i++) {if (i == pageNo) {sb.append("<li class=\"active\"><a href=\"javascript:\">" + (i + 1 - first)+ "</a></li>\n");} else {sb.append("<li><a href=\"javascript:\" οnclick=\""+funcName+"("+i+","+pageSize+",'"+funcParam+"');\">"+ (i + 1 - first) + "</a></li>\n");}}if (last - end > slider) {sb.append("<li class=\"disabled\"><a href=\"javascript:\">...</a></li>\n");end = last - slider;}for (int i = end + 1; i <= last; i++) {sb.append("<li><a href=\"javascript:\" οnclick=\""+funcName+"("+i+","+pageSize+",'"+funcParam+"');\">"+ (i + 1 - first) + "</a></li>\n");}if (pageNo == last) {sb.append("<li class=\"disabled\"><a href=\"javascript:\">下一页 »</a></li>\n");} else {sb.append("<li><a href=\"javascript:\" οnclick=\""+funcName+"("+next+","+pageSize+",'"+funcParam+"');\">"+ "下一页 »</a></li>\n");}return sb.toString();}/*** 获取分页HTML代码* @return*/public String getHtml(){return toString();}/*** 获取设置总数* @return*/public long getCount() {return count;}/*** 设置数据总数* @param count*/public void setCount(long count) {this.count = count;if (pageSize >= count){pageNo = 1;}}/*** 获取当前页码* @return*/public int getPageNo() {return pageNo;}/*** 设置当前页码* @param pageNo*/public void setPageNo(int pageNo) {this.pageNo = pageNo;}/*** 获取页面大小* @return*/public int getPageSize() {return pageSize;}/*** 设置页面大小（最大500）// > 500 ? 500 : pageSize;* @param pageSize*/public void setPageSize(int pageSize) {this.pageSize = pageSize <= 0 ? 10 : pageSize;}/*** 首页索引* @return*/@JsonIgnorepublic int getFirst() {return first;}/*** 尾页索引* @return*/@JsonIgnorepublic int getLast() {return last;}/*** 获取页面总数* @return getLast();*/@JsonIgnorepublic int getTotalPage() {return getLast();}/*** 是否为第一页* @return*/@JsonIgnorepublic boolean isFirstPage() {return firstPage;}/*** 是否为最后一页* @return*/@JsonIgnorepublic boolean isLastPage() {return lastPage;}/*** 上一页索引值* @return*/@JsonIgnorepublic int getPrev() {if (isFirstPage()) {return pageNo;} else {return pageNo - 1;}}/*** 下一页索引值* @return*/@JsonIgnorepublic int getNext() {if (isLastPage()) {return pageNo;} else {return pageNo + 1;}}/*** 获取本页数据对象列表* @return List<T>*/public List<T> getList() {return list;}/*** 设置本页数据对象列表* @param list*/public Page<T> setList(List<T> list) {this.list = list;initialize();return this;}/*** 获取查询排序字符串* @return*/@JsonIgnorepublic String getOrderBy() {// SQL过滤，防止注入 String reg = "(?:')|(?:--)|(/\\*(?:.|[\\n\\r])*?\\*/)|"+ "(\\b(select|update|and|or|delete|insert|trancate|char|into|substr|ascii|declare|exec|count|master|into|drop|execute)\\b)";Pattern sqlPattern = Pattern.compile(reg, Pattern.CASE_INSENSITIVE);if (sqlPattern.matcher(orderBy).find()) {return "";}return orderBy;}/*** 设置查询排序，标准查询有效， 实例： updatedate desc, name asc*/public void setOrderBy(String orderBy) {this.orderBy = orderBy;}/*** 获取点击页码调用的js函数名称* function ${page.funcName}(pageNo){location="${ctx}/list-${category.id}${urlSuffix}?pageNo="+i;}* @return*/@JsonIgnorepublic String getFuncName() {return funcName;}/*** 设置点击页码调用的js函数名称，默认为page，在一页有多个分页对象时使用。* @param funcName 默认为page*/public void setFuncName(String funcName) {this.funcName = funcName;}/*** 获取分页函数的附加参数* @return*/@JsonIgnorepublic String getFuncParam() {return funcParam;}/*** 设置分页函数的附加参数* @return*/public void setFuncParam(String funcParam) {this.funcParam = funcParam;}/*** 设置提示消息，显示在“共n条”之后* @param message*/public void setMessage(String message) {this.message = message;}/*** 分页是否有效* @return this.pageSize==-1*/@JsonIgnorepublic boolean isDisabled() {return this.pageSize==-1;}/*** 是否进行总数统计* @return this.count==-1*/@JsonIgnorepublic boolean isNotCount() {return this.count==-1;}/*** 获取 Hibernate FirstResult*/public int getFirstResult(){int firstResult = (getPageNo() - 1) * getPageSize();if (firstResult >= getCount()) {firstResult = 0;}return firstResult;}/*** 获取 Hibernate MaxResults*/public int getMaxResults(){return getPageSize();}}

看完这个Page对象应该稍微有点感觉了吧，然后我在胡乱贴一些相关用到的工具类吧，工具类的话我只稍微提一下，具体大家可以弄到自己的代码上好好解读。

PropertiesLoader.java 用来获取resource文件夹下的常量配置文件

package com.store.base.secondmodel.base.util;import java.io.IOException;
import java.io.InputStream;
import java.util.NoSuchElementException;
import java.util.Properties;import org.apache.commons.io.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.io.DefaultResourceLoader;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;/*** Properties文件载入工具类. 可载入多个properties文件, * 相同的属性在最后载入的文件中的值将会覆盖之前的值，但以System的Property优先.* @author **/
public class PropertiesLoader {private static Logger logger = LoggerFactory.getLogger(PropertiesLoader.class);private static ResourceLoader resourceLoader = new DefaultResourceLoader();private final Properties properties;public PropertiesLoader(String... resourcesPaths) {properties = loadProperties(resourcesPaths);}public Properties getProperties() {return properties;}/*** 取出Property，但以System的Property优先,取不到返回空字符串.*/private String getValue(String key) {String systemProperty = System.getProperty(key);if (systemProperty != null) {return systemProperty;}if (properties.containsKey(key)) {return properties.getProperty(key);}return "";}/*** 取出String类型的Property，但以System的Property优先,如果都为Null则抛出异常.*/public String getProperty(String key) {String value = getValue(key);if (value == null) {throw new NoSuchElementException();}return value;}/*** 取出String类型的Property，但以System的Property优先.如果都为Null则返回Default值.*/public String getProperty(String key, String defaultValue) {String value = getValue(key);return value != null ? value : defaultValue;}/*** 取出Integer类型的Property，但以System的Property优先.如果都为Null或内容错误则抛出异常.*/public Integer getInteger(String key) {String value = getValue(key);if (value == null) {throw new NoSuchElementException();}return Integer.valueOf(value);}/*** 取出Integer类型的Property，但以System的Property优先.如果都为Null则返回Default值，如果内容错误则抛出异常*/public Integer getInteger(String key, Integer defaultValue) {String value = getValue(key);return value != null ? Integer.valueOf(value) : defaultValue;}/*** 取出Double类型的Property，但以System的Property优先.如果都为Null或内容错误则抛出异常.*/public Double getDouble(String key) {String value = getValue(key);if (value == null) {throw new NoSuchElementException();}return Double.valueOf(value);}/*** 取出Double类型的Property，但以System的Property优先.如果都为Null则返回Default值，如果内容错误则抛出异常*/public Double getDouble(String key, Integer defaultValue) {String value = getValue(key);return value != null ? Double.valueOf(value) : defaultValue.doubleValue();}/*** 取出Boolean类型的Property，但以System的Property优先.如果都为Null抛出异常,如果内容不是true/false则返回false.*/public Boolean getBoolean(String key) {String value = getValue(key);if (value == null) {throw new NoSuchElementException();}return Boolean.valueOf(value);}/*** 取出Boolean类型的Property，但以System的Property优先.如果都为Null则返回Default值,如果内容不为true/false则返回false.*/public Boolean getBoolean(String key, boolean defaultValue) {String value = getValue(key);return value != null ? Boolean.valueOf(value) : defaultValue;}/*** 载入多个文件, 文件路径使用Spring Resource格式.*/private Properties loadProperties(String... resourcesPaths) {Properties props = new Properties();for (String location : resourcesPaths) {InputStream is = null;try {Resource resource = resourceLoader.getResource(location);is = resource.getInputStream();props.load(is);} catch (IOException ex) {logger.error("Could not load properties from path:" + location , ex);} finally {IOUtils.closeQuietly(is);}}return props;}
}

Global.java 用来获取全局的一些常量，可以是从配置文件中读取的常量，也可以是定义成final static的常量，获取配置文件的话是调用上面那个类进行获取的。

package com.store.base.secondmodel.base;import java.io.File;
import java.io.IOException;
import java.util.Map;import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.io.DefaultResourceLoader;import com.google.common.collect.Maps;
import com.store.base.secondmodel.base.util.PropertiesLoader;
import com.store.base.secondmodel.base.util.StringUtils;/*** 全局配置类* @author **/
public class Global {private static final Logger logger = LoggerFactory.getLogger(Global.class);/*** 当前对象实例*/private static Global global = new Global();/*** 保存全局属性值*/private static Map<String, String> map = Maps.newHashMap();/*** 属性文件加载对象*/private static PropertiesLoader loader = new PropertiesLoader("application.properties");/*** 显示/隐藏public static final String SHOW = "1";public static final String HIDE = "0";/*** 是/否*/public static final String YES = "1";public static final String NO = "0";/*** 状态 上/下 app专用*/public static final String UPSHVELF = "1";public static final String DOWNSHVELF = "2";public static final String SEPARATOR = "/";/*** 对/错*/public static final String TRUE = "true";public static final String FALSE = "false";/*** 上传文件基础虚拟路径*/public static final String USERFILES_BASE_URL = "/userfiles/";/*** 针对富文本编辑器，结尾会产生的空div*/public static final String ENDS = "<p><br></p>";/*** 默认空的私有构造函数*/public Global() {//do nothing in this method,just empty}/*** 获取当前对象实例*/public static Global getInstance() {return global;}/*** 获取配置*/public static String getConfig(String key) {String value = map.get(key);if (value == null){value = loader.getProperty(key);map.put(key, value != null ? value : StringUtils.EMPTY);}return value;}/*** 获取URL后缀*/public static String getUrlSuffix() {return getConfig("urlSuffix");}/*** 页面获取常量* @see ${fns:getConst('YES')}*/public static Object getConst(String field) {try {return Global.class.getField(field).get(null);} catch (Exception e) {logger.error("获取常量出错", e);}return null;}/*** 获取工程路径* @return*/public static String getProjectPath(){// 如果配置了工程路径，则直接返回，否则自动获取。String projectPath = Global.getConfig("projectPath");if (StringUtils.isNotBlank(projectPath)){return projectPath;}try {File file = new DefaultResourceLoader().getResource("").getFile();if (file != null){while(true){File f = new File(file.getPath() + File.separator + "src" + File.separator + "main");if (f == null || f.exists()){break;}if (file.getParentFile() != null){file = file.getParentFile();}else{break;}}projectPath = file.toString();}} catch (IOException e) {logger.error("加载配置文件失败", e);}return projectPath;}}

CookieUtil.java 从名称就知道是针对获取和存储cookie的一个工具类

package com.store.base.secondmodel.base.util;import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import org.slf4j.Logger;
import org.slf4j.LoggerFactory;/*** Cookie工具类* @author **/
public class CookieUtils {private static final Logger logger = LoggerFactory.getLogger(CookieUtils.class);/*** 私有构造函数*/private CookieUtils() {}/*** 设置 Cookie（生成时间为1年）* @param name 名称* @param value 值*/public static void setCookie(HttpServletResponse response, String name, String value) {setCookie(response, name, value, 60*60*24*365);}/*** 设置 Cookie* @param name 名称* @param value 值* @param maxAge 生存时间（单位秒）* @param uri 路径*/public static void setCookie(HttpServletResponse response, String name, String value, String path) {setCookie(response, name, value, path, 60*60*24*365);}/*** 设置 Cookie* @param name 名称* @param value 值* @param maxAge 生存时间（单位秒）* @param uri 路径*/public static void setCookie(HttpServletResponse response, String name, String value, int maxAge) {setCookie(response, name, value, "/", maxAge);}/*** 设置 Cookie* @param name 名称* @param value 值* @param maxAge 生存时间（单位秒）* @param uri 路径*/public static void setCookie(HttpServletResponse response, String name, String value, String path, int maxAge) {Cookie cookie = new Cookie(name, null);cookie.setPath(path);cookie.setMaxAge(maxAge);try {cookie.setValue(URLEncoder.encode(value, "utf-8"));} catch (UnsupportedEncodingException e) {logger.error("不支持的编码", e);}response.addCookie(cookie);}/*** 获得指定Cookie的值* @param name 名称* @return 值*/public static String getCookie(HttpServletRequest request, String name) {return getCookie(request, null, name, false);}/*** 获得指定Cookie的值，并删除。* @param name 名称* @return 值*/public static String getCookie(HttpServletRequest request, HttpServletResponse response, String name) {return getCookie(request, response, name, true);}/*** 获得指定Cookie的值* @param request 请求对象* @param response 响应对象* @param name 名字* @param isRemove 是否移除* @return 值*/public static String getCookie(HttpServletRequest request, HttpServletResponse response, String name, boolean isRemove) {String value = null;Cookie[] cookies = request.getCookies();if(cookies == null) {return value;}for (Cookie cookie : cookies) {if (cookie.getName().equals(name)) {try {value = URLDecoder.decode(cookie.getValue(), "utf-8");} catch (UnsupportedEncodingException e) {logger.error("不支持的编码", e);}if (isRemove) {cookie.setMaxAge(0);response.addCookie(cookie);}}}return value;}
}

SpringContextHolder.java 主要是用来在java代码中获取当前的ApplicationContext，需要在spring配置文件中配置这个bean并且懒加载设置成false；

package com.store.base.secondmodel.base.util;import org.apache.commons.lang3.Validate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.annotation.Lazy;
import org.springframework.stereotype.Service;@Service
@Lazy(false)
public class SpringContextHolder implements ApplicationContextAware,DisposableBean {private static Logger logger = LoggerFactory.getLogger(SpringContextHolder.class);private static ApplicationContext applicationContext = null;/*** 取得存储在静态变量中的ApplicationContext.*/public static ApplicationContext getApplicationContext() {assertContextInjected();return applicationContext;}/*** 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.*/@SuppressWarnings("unchecked")public static <T> T getBean(String name) {assertContextInjected();return (T) applicationContext.getBean(name);}/*** 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.*/public static <T> T getBean(Class<T> requiredType) {assertContextInjected();return applicationContext.getBean(requiredType);}@Overridepublic void destroy() throws Exception {SpringContextHolder.clearHolder();}/*** 实现ApplicationContextAware接口, 注入Context到静态变量中.*/@Overridepublic void setApplicationContext(ApplicationContext applicationContext) {logger.debug("注入ApplicationContext到SpringContextHolder:{}", applicationContext);SpringContextHolder.applicationContext = applicationContext;if (SpringContextHolder.applicationContext != null) {logger.info("SpringContextHolder中的ApplicationContext被覆盖, 原有ApplicationContext为:" + SpringContextHolder.applicationContext);}}/*** 清除SpringContextHolder中的ApplicationContext为Null.*/public static void clearHolder() {if (logger.isDebugEnabled()){logger.debug("清除SpringContextHolder中的ApplicationContext:" + applicationContext);}applicationContext = null;}/*** 检查ApplicationContext不为空.*/private static void assertContextInjected() {Validate.validState(applicationContext != null, "applicaitonContext属性未注入, 请在applicationContext.xml中定义SpringContextHolder.");}}

StringUtils.java字符串相关的一个工具类

package com.store.base.secondmodel.base.util;import java.io.UnsupportedEncodingException;
import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;import javax.servlet.http.HttpServletRequest;import org.apache.commons.lang3.StringEscapeUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;
import org.springframework.web.servlet.LocaleResolver;import com.store.base.util.Encodes;/*** 字符串帮助类* @author **/
public class StringUtils extends org.apache.commons.lang3.StringUtils {private static final char SEPARATOR = '_';private static final String CHARSET_NAME = "UTF-8";private static final Logger logger = LoggerFactory.getLogger(StringUtils.class);/*** 转换为字节数组* @param str* @return*/public static byte[] getBytes(String str){if (str != null){try {return str.getBytes(CHARSET_NAME);} catch (UnsupportedEncodingException e) {logger.error("", e);return new byte[0];}}else{return new byte[0];}}/*** 转换为字节数组* @param str* @return*/public static String toString(byte[] bytes){try {return new String(bytes, CHARSET_NAME);} catch (UnsupportedEncodingException e) {logger.error("", e);return EMPTY;}}/*** 是否包含字符串* @param str 验证字符串* @param strs 字符串组* @return 包含返回true*/public static boolean inString(String str, String... strs){if (str != null){for (String s : strs){if (str.equals(trim(s))){return true;}}}return false;}/*** 替换掉HTML标签方法*/public static String replaceHtml(String html) {if (isBlank(html)){return "";}String regEx = "<.+?>";Pattern p = Pattern.compile(regEx);Matcher m = p.matcher(html);return m.replaceAll("");}/*** 替换为手机识别的HTML，去掉样式及属性，保留回车。* @param html* @return*/public static String replaceMobileHtml(String html){if (html == null){return "";}return html.replaceAll("<([a-z]+?)\\s+?.*?>", "<$1>");}/*** 替换为手机识别的HTML，去掉样式及属性，保留回车。* @param txt* @return*/public static String toHtml(String txt){if (txt == null){return "";}return replace(replace(Encodes.escapeHtml(txt), "\n", "<br/>"), "\t", "    ");}/*** 缩略字符串（不区分中英文字符）* @param str 目标字符串* @param length 截取长度* @return*/public static String abbr(String str, int length) {if (str == null) {return "";}try {StringBuilder sb = new StringBuilder();int currentLength = 0;for (char c : replaceHtml(StringEscapeUtils.unescapeHtml4(str)).toCharArray()) {currentLength += String.valueOf(c).getBytes("GBK").length;if (currentLength <= length - 3) {sb.append(c);} else {sb.append("...");break;}}return sb.toString();} catch (UnsupportedEncodingException e) {logger.error("", e);}return "";}/*** 转换为Double类型*/public static Double toDouble(Object val){if (val == null){return 0D;}try {return Double.valueOf(trim(val.toString()));} catch (Exception e) {logger.error("", e);return 0D;}}/*** 转换为Float类型*/public static Float toFloat(Object val){return toDouble(val).floatValue();}/*** 转换为Long类型*/public static Long toLong(Object val){return toDouble(val).longValue();}/*** 转换为Integer类型*/public static Integer toInteger(Object val){return toLong(val).intValue();}/*** 获得i18n字符串*/public static String getMessage(String code, Object[] args) {LocaleResolver localLocaleResolver = SpringContextHolder.getBean(LocaleResolver.class);HttpServletRequest request = ((ServletRequestAttributes)RequestContextHolder.getRequestAttributes()).getRequest();  Locale localLocale = localLocaleResolver.resolveLocale(request);return SpringContextHolder.getApplicationContext().getMessage(code, args, localLocale);}/*** 获得用户远程地址*/public static String getRemoteAddr(HttpServletRequest request){String remoteAddr = request.getHeader("X-Real-IP");if (isNotBlank(remoteAddr)) {remoteAddr = request.getHeader("X-Forwarded-For");}if (isNotBlank(remoteAddr)) {remoteAddr = request.getHeader("Proxy-Client-IP");}if (isNotBlank(remoteAddr)) {remoteAddr = request.getHeader("WL-Proxy-Client-IP");}return remoteAddr != null ? remoteAddr : request.getRemoteAddr();}/*** 驼峰命名法工具* @return*        toCamelCase("hello_world") == "helloWorld" *      toCapitalizeCamelCase("hello_world") == "HelloWorld"*         toUnderScoreCase("helloWorld") = "hello_world"*/public static String toCamelCase(String s) {String s1 =s;if (s1 == null) {return null;}s1 = s.toLowerCase();StringBuilder sb = new StringBuilder(s1.length());boolean upperCase = false;for (int i = 0; i < s1.length(); i++) {char c = s1.charAt(i);if (c == SEPARATOR) {upperCase = true;} else if (upperCase) {sb.append(Character.toUpperCase(c));upperCase = false;} else {sb.append(c);}}return sb.toString();}/*** 驼峰命名法工具* @return*      toCamelCase("hello_world") == "helloWorld" *      toCapitalizeCamelCase("hello_world") == "HelloWorld"*         toUnderScoreCase("helloWorld") = "hello_world"*/public static String toCapitalizeCamelCase(String s) {String s1 = s;if (s1 == null) {return null;}s1 = toCamelCase(s1);return s1.substring(0, 1).toUpperCase() + s1.substring(1);}/*** 驼峰命名法工具* @return*         toCamelCase("hello_world") == "helloWorld" *      toCapitalizeCamelCase("hello_world") == "HelloWorld"*         toUnderScoreCase("helloWorld") = "hello_world"*/public static String toUnderScoreCase(String s) {if (s == null) {return null;}StringBuilder sb = new StringBuilder();boolean upperCase = false;for (int i = 0; i < s.length(); i++) {char c = s.charAt(i);boolean nextUpperCase = true;if (i < (s.length() - 1)) {nextUpperCase = Character.isUpperCase(s.charAt(i + 1));}if ((i > 0) && Character.isUpperCase(c)) {if (!upperCase || !nextUpperCase) {sb.append(SEPARATOR);}upperCase = true;} else {upperCase = false;}sb.append(Character.toLowerCase(c));}return sb.toString();}/*** 转换为JS获取对象值，生成三目运算返回结果* @param objectString 对象串*   例如：row.user.id*   返回：!row?'':!row.user?'':!row.user.id?'':row.user.id*/public static String jsGetVal(String objectString){StringBuilder result = new StringBuilder();StringBuilder val = new StringBuilder();String[] vals = split(objectString, ".");for (int i=0; i<vals.length; i++){val.append("." + vals[i]);result.append("!"+(val.substring(1))+"?'':");}result.append(val.substring(1));return result.toString();}}

有了上面这些基础的东西，只需要在写一个控制层接口，就可以看到每次返回一个page对象，然后里面封装好了查询对象的列表，并且是按分页得出列表。

package com.store.controller;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;import com.store.base.secondmodel.base.Page;
import com.store.base.secondmodel.pratice.model.Product;
import com.store.base.secondmodel.pratice.service.ProductService;/***TODO*2016年10月11日**/
@RestController
@RequestMapping("/product")
public class ProductController {@Autowiredprivate ProductService productService;@ResponseBody@RequestMapping(value="/getPageProduct")public Page<Product> getPageProduct(HttpServletRequest request,HttpServletResponse response){Page<Product> page =  productService.findPage(new Page<Product>(request,response), new Product());return page;}}

最后在看一下页面怎么使用这个page对象，这样我们就完整地介绍了这个一个分页功能，代码很多，但很完整。

<%@ page contentType="text/html;charset=UTF-8"%>
<%@ include file="/WEB-INF/views/include/taglib.jsp"%>
<html>
<head><title></title><meta name="decorator" content="default" />function page(n, s) {if (n)$("#pageNo").val(n);if (s)$("#pageSize").val(s);$("#searchForm").attr("action", "${ctx}/app/bank/list");$("#searchForm").submit();return false;}</script>
</head>
<body><form:form id="searchForm" modelAttribute="XXXX" action="${ctx}/XXX" method="post" class="breadcrumb form-search "><input id="pageNo" name="pageNo" type="hidden" value="${page.pageNo}" /><input id="pageSize" name="pageSize" type="hidden" value="${page.pageSize}" /><ul class="ul-form"><li><label>是否上架：</label><form:select id="status" path="status" class="input-medium"><form:option value="" label=""/><form:options items="${fns:getDictList('yes_no_app')}" itemLabel="label" itemValue="value" htmlEscape="false"/></form:select></li><li class="btns"><input id="btnSubmit" class="btn btn-primary" type="submit" value="查询"/><li class="clearfix"></li></ul></form:form><sys:message content="${message}" /><sys:message content="${message}" /><table id="contentTable"class="table table-striped table-bordered table-condensed"><thead><tr><th>XXXX</th><th>XXXX</th><th>XXXX</th><th>XXXX</th><th>XXXX</th><th>XXXX</th><th>XXXX</th><th>XXXX</th></tr></thead><tbody><c:forEach items="${page.list}" var="XXXX"><tr><td>${XXXX.name}</td><td><a href="${ctx}/app/bank/form?id=${XXXX.id}">${XXXX.}</a></td><td>${XXXX.}</td><td>${XXXX.}</td><td>${XXXX.}</td><td>${fns:getDictLabel(XXXX.isHot, 'yes_no_app', '无')}</td><td>${XXXX.}</td><td><c:if test="${XXXX.status==1 }">上架</c:if><c:if test="${XXXX.status==2 }">下架</c:if></td>                           </tr></c:forEach></tbody></table><div class="pagination">${page} <li style="padding-top: 6px;padding-left: 12px;float: left;">共${page.count}条</li></div>
</body>
</html>

到这里就基本上把整个分页功能描述得比较清楚了，希望可以帮助到你们快速解决分页这个问题，当然要在前端显示分页漂亮的话要针对li做一些css样式啥的，最后祝福你可以快速掌握这个分页功能！

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